We are going to show you, how to design a simple
Battery Level Indicator Circuit using LM 3914. The battery level indicator indicates the status of the battery by a glowing LED. In this circuit, we have 9 LED that show the level of the battery. The battery level indicator circuit increases the lifetime of the battery because this circuit indicates your battery is full or overcharged or empty.
This simple and easy project explains to you how to design
battery level indicators using LM3914 with a few other components.
10 LED’s (Red – 3, Yellow – 4, Green – 3)
Resistors – 18K, 4.7K, 56K
Potentiometer – 10K
12V Battery (for testing)
2 point connectors
Battery Level Indicator Circuit Diagram
Battery Charge Indicator Circuit Design
In this circuit D1 to D10 LEDs displays the capacity of the battery dot bar display can also be used for indication instead of LEDs. External switch sw1 is used to select the mode, sw1 is connected to the 9
th pin of LM39-14-IC. The 6 th and 7 th pins are connected to the ground through an (R1) resistor. This resistor controls the brightness of LEDs. Resistor R3 and RV1 are formed a potential divider circuit. Here RV1 is used for calibration. There is no need for an external power supply to operate this circuit.
The circuit is designed to monitor the current 10V to 15V DC. The operating voltage of this IC-LM3914 is 3v to 25v DC, so this circuit will work even on 3v. The IC-LM3914 contains adjustable reference and an accurate 10-steps divider. This IC-LM3914 can also act as a sequencer.
Battery Level Indicator Circuit Principle
LM3914 is the heart of this battery level indicator circuit. Lm3914 takes input analog voltage and drives 10 LED’s. There is no need for resistors in series with LEDs for protection because the current is regulated by the IC.
Internal voltage reference from 1.2v to 12v DC.
Outputs current regulated for LEDs.
Programmable current output 2mA to 30mA.
No interaction between outputs.
It supports temperature from 0 to 70 degrees Celsius.
Connect the 9
th pin of IC to the supply for bar graph display. Leave the 9
th pin of IC for dot display.
How to Operate Battery Level Indicator Circuit?
Connect battery wires to the input of the circuit.
Now adjust the pot so that LED D1 just starts glowing.
Increase the input voltage slowly and observe the LED’s
The first led will glow for 1.2V and the second LED is for 1.4 V and so on.
Limitations of the Circuit
This battery level indicator circuit works only for small voltages.
The circuit is theoretical and may require some changes to work in practice.
We can make little change by change in resistors
This circuit can be used for other voltage battery
We can use this circuit to measure other voltage ranges also with little modifications. We have removed the resistor R2 and connect the upper voltage level to the input. Now vary the resistance of Pot RV1 till the D10 LED glows. Remove upper voltage level at the input and connect the lower voltage level. Connect a high value (pot) variable resistor in the place of resistor 18k and move it till the D1 LED glows. Now disconnect the pot and measure the resistance across it and connect a resistor of the same value in place of R2. Now the circuit is ready to monitor other voltage ranges according to you’re desired.
This circuit most suitable for 12v battery measurement because LEDs glow every 10%.